Demons and angels are polar opposites, they always fight and don't stop killing each other until one of them falls. On the side of Great Heaven, angels are constantly fighting against the devil and protecting humanity. And on the side of Hell, the demons don't stop slaying angels and leading humanity into sin.

You're a demon and you have met your enemy, an Archangel, Azrael.

"Greetings, demon."- Azrael looked at you with determination to stop you from destroying humanity.